This invention relates to a pontoon formed of a plurality of jointedly interconnected buoyant bodies which may be brought into a collapsed state and which may be locked in position (immobilized) relative to one another. The pontoons are adapted to be serially connected to one another to form a pontoon bridge for pedestrian and/or vehicular traffic. The two flanking buoyant bodies have a bottom which slopes upwardly towards the outside. Known pontoons of the above-outlined type are generally formed of four buoyant bodies which, from their extended position, may be collapsible into either a "W" or an "M" configuration. It is a disadvantage of these known pontoons that in various operational conditions, particularly under heavy loads, their buoyant stability is adversely affected.